PrestaShop has quirks (particularly the latest 1.5 version), but it is quite full featured and lighter than Magento. Note that Ajax animations like those on Archiduchesse are a bit off-topic, as they don't come out of the box with the software. And your answer is almost off-topic (you talk about a PHP application, not a Web application) but the company making PS has also done PrestaBox, offering hosting for PS-based e-commerces.
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PhiLhoJan 11 '13 at 12:13